To solve this issue, I mounted a 1500w 120v heating element in my kettle, which plugs directly into a GFCI outlet (no output control, it's always at 100%). This, combined with about 80% heat on my largest burner (which I replaced with a 2600w canning element to give extra power and support the weight of the kettle) lets me get 7.5 gallons or so to a rolling boil in under half an hour.

What's big? I've done 5 gallon batches on the stove. Takes some work but it gets there eventually. You looking to do bigger than that?

Personally I'd look into alternatives to the kitchen stove if it's bigger than 5 gallons. Just my 2 cents.

There are fish steamer/poacher pans out there that are oblong but I doubt they are anywhere near the volume needed.

Also the weight might be a concern. For a 10 gallon batch you're looking at 12+ gallons of wort. So close to a 100 pounds of wort on the burner that really isn't made to support that kind of weight. There is a canning element out there that will fit most electric ranges but that's still only made to handle the 20 quart canning pots. The canning elements are about the same as your regular element in terms of wattage but have a heavier base.

I have a really solid gas stove so I am not worried about the weight of the liquid.

I am looking to do two parallel 6 gallon boils.

I am typically starting with 6 gallon boil volumes on the stove's so called power burner which is about 50% larger than the other burners. This works pretty well and I am reasonably happy with it. I would like to do another 6 gallon boil next to this, to brew two separate batches at once however I am stuck with using the smaller burners. Ideally I would like to collect the heat from two burners at once but the pot is not really big enough to do this efficiently. Getting round pot that is large enough two cover both burners would be so large it would also sit on my counter.

I've got an enamel canning pot that i picked up second hand. It holds seven gallons and sets across two burners. Unfortunately, i'm not sure where you could get one of these new; but, at least you know they're out there!

Ah ok. Well not sure in that case. Have you tried a boil on the smaller burner? Gas flames spread out the heat really well and there should be plenty of BTU's from it to do the job. Not sure what else to suggest. Sorry I'm not more helpful.

I have a really solid gas stove so I am not worried about the weight of the liquid.

I am looking to do two parallel 6 gallon boils.

I am typically starting with 6 gallon boil volumes on the stove's so called power burner which is about 50% larger than the other burners. This works pretty well and I am reasonably happy with it. I would like to do another 6 gallon boil next to this, to brew two separate batches at once however I am stuck with using the smaller burners. Ideally I would like to collect the heat from two burners at once but the pot is not really big enough to do this efficiently. Getting round pot that is large enough two cover both burners would be so large it would also sit on my counter.

Thanks for the feedback.

I use three - five gallon pots for that amount. My wife and mother-in-law picked them up as Xmas gifts for me. They cost about $8.00 each.